[symfony] FormType - setDefaultOptions

public function setDefaultOptions(OptionsResolverInterface $resolver)

    {

        parent::setDefaultOptions($resolver);

        // Constraint should always be converted to an array

        $constraintsNormalizer = function (Options $options, $constraints) {

            return is_object($constraints) ? array($constraints) : (array) $constraints;

        };

        $resolver->setDefaults(array(

            'error_mapping'              => array(),

            'constraints'                => array(),

            'cascade_validation'         => false,

            'invalid_message'            => 'This value is not valid.',

            'invalid_message_parameters' => array(),

            'extra_fields_message'       => 'This form should not contain extra fields.',

        ));

        $resolver->setNormalizers(array(

            'constraints'       => $constraintsNormalizer,

        ));

    }